1. Field of the Invention
This invention relates to a semiconductor device having a structure of stacked layers of semiconductor dice.
2. Description of the Related Art
The semiconductor device having the structure of stacked layers of semiconductor dice (hereafter referred to as a stacked layer structure) has been known from a standpoint of seeking higher integration and further size reduction of the semiconductor device. An example of conventional semiconductor device having the stacked layer structure will be explained referring to the drawings. FIG. 9 is a cross-sectional view showing an outline of the conventional semiconductor device 100 having the stacked layer structure.
The semiconductor device 100 has the structure of stacked layers of semiconductor dice (a first semiconductor die 101, a second semiconductor die 102 and a third semiconductor die 103). Each of the semiconductor dice 101, 102 and 103 is provided with a semiconductor substrate 104 made of silicon (Si) or the like device elements 105 composed of a multitude of elements such as MOS transistors and capacitors formed on one of surfaces of the semiconductor substrate 104, through holes 106 penetrating through the semiconductor substrate 104, through hole electrodes 107 each formed in each of the through holes 106 and conductive terminals 108 each made of solder or the like and connected with each of the through hole electrodes 107. The semiconductor dice 101, 102 and 103 are electrically connected with each other through the through hole electrodes 107 and the conductive terminals 108.
Following method has been proposed as a manufacturing method of the semiconductor device 100 that has the stacked layer structure described above. The individual semiconductor device 100 is obtained through process steps to sequentially stack semiconductor substrates 109 in wafer form, in which the device elements 105, the through holes 106, the through hole electrodes 107 and the conductive terminals 108 are already formed and subsequent process steps to continuously cut each of the semiconductor substrates 109 along a dicing line DL that makes a border between the individual semiconductor devices 100.
The technology mentioned above is described in Japanese Patent Application Publication No. 2005-347442, for example.
However, the conventional semiconductor device 100 shown in FIG. 9 is vulnerable to lateral mechanical stress which would peel off the stacked layer of semiconductor die in some cases. Especially, the closer to a top layer, the more vulnerable the semiconductor die is against the mechanical stress. As a result, there has been a problem that the stacked layer structure is destroyed to cause a failure in the semiconductor device while the semiconductor device is in field use or in manufacturing. Note that the problem is increasingly apparent when a larger number of semiconductor dice are stacked, because even a single failed die out of the semiconductor dice constituting the stacked layer structure causes a failure of the device as a whole.
In addition, there has been a problem that a corrosive material such as a chemical solution or water infiltrates into the semiconductor device to deteriorate a metal portion (the conductive terminal 108 or a wiring formed on a surface or a back surface of the semiconductor die) constituting each of the semiconductor dice 101, 102 and 103, reducing the reliability and yield of the semiconductor device.
As described above, the process steps to stack the semiconductor substrates 109 in the wafer form has been conceived to be included in the manufacturing method of the semiconductor device 100. However, even a single failed die out of the semiconductor dice constituting the stacked layer structure causes a failure of the device as a whole. The failed die is formed at a random location in the semiconductor substrate in wafer form. With the manufacturing method described above, therefore, there has been a problem that the yield and reliability of finally completed semiconductor devices are low.
This invention is directed to offering a semiconductor device having the stacked layer structure and its manufacturing method that bring high yield and reliability.